Working on your clients' live stores
There are a few different ways that you can work on a store's theme without your changes immediately affecting the live site.
Option 1: Duplicate the theme
If you duplicate a theme from the Themes page in the merchant's Shopify admin, then you can customize that duplicate version of the theme directly in Shopify without your changes appearing on the online store. When you're ready to launch the updated theme, you can publish it.
Option 2: Download the theme
If you download the theme from the Themes page in the Shopify admin, then you can make changes to the theme files by using a text editor or web development tool. When you're ready to launch the updated theme, you can upload it, and then set it as the current theme.
Option 3: Use Shopify Theme Kit
You can use Shopify Theme Kit to modify your theme with a local text editor of your choice. It then pushes your edits to your development store using our API.
Shopify supports multiple themes, so you can make a copy of your theme on the Themes page in your Shopify admin, and edit that unpublished theme.